Light guide devices are known in the art and are utilised, by way of example, for illumination, backlighting, signage and display purposes. Typically, a light guiding device comprises a light source such as a fluorescent lamp or a plurality of light emitting diodes (LEDs) and a light guide plate which is constructed from a standard injection-moulded or machined transparent plastic component.
The light guide plate will often comprise suitable structural surface modifications which disturb the total internal reflection of the light from the light source such that the light is guided through the transparent light guide in a controlled manner and emitted in a substantially perpendicular direction to that of the direction of propagation of light within the transparent guide.
However, there are a number of problems associated with the manufacture of such a light guide plate. For instance, an injection-moulded light guide comprising these surface features requires a suitable mould to be micro-machined or laser cut, often at great cost.
Other techniques useful for preparing light guide plates include micro-stamping or hot embossing of suitable polymer sheets. However, the optical quality of the end light guide is restricted by the stamp quality and associated manufacturing process.
Furthermore, the micro-mechanical surface features described may easily be damaged during production of the light guide plate, or during assembly of a light guide device. In addition, stringent dust-free production and assembly processes are required to ensure that no dust particles are collected on the surface features, which may have an adverse effect on light propagation through the light guide. Consequently, production costs and assembly process costs are high.
Due to the increasing size of display units and therefore increasing size of backlights required for use in these units, the physical limitations of the manufacturing and assembly processes become more critical and the associated costs increase. There is therefore an ongoing need for alternative and/or improved light guide plates and devices and methods of formation thereof for use in, inter alia, backlighting applications.
It is an object of the present invention to provide a light guide plate that addresses one or more of the aforesaid disadvantages.